A Team: Are those contrails or chemtrails trailing airplanes over Anderson?

Q: There were several trails of clouds behind airplanes over Anderson early this week. Are those chemicals being dumped into the air?

A: Contrary to widespread theories that the jetliners, military and privately owned planes are secretly dumping chemicals into the air, aviation experts agree that contrails — short for condensation trails, those linear clouds often trailing an aircraft — are natural and harmless.

Contrails are the result of the warm, moist exhaust of the plane's engines meeting the extremely cold temperatures of the upper atmosphere. It's a similar principle behind why you can see your breath on cold mornings.

As the jet fuel is burned, atoms bond with the oxygen in the air to form water vapor, which clings the tiny materials (aerosols, sulfates, soot, carbon dioxide and other items) that are part of jet fuel exhaust.

Contrails appear and disappear based on the moisture content of the air surrounding the plane. If the upper atmospheric air is moist, the plane will leave a contrail that could last hours; if the air is extremely dry, it might not leave a contrail at all.

Contrail formation can also vary depending on the air temperature, which at the cruising altitude of a jetliner (30,000 feet), can be as cold as -40 degrees Fahrenheit, a point where water vapor freezes instantly. By contrast, aircraft at ground level in the Arctic produces a contrail while on the ground.

The same phenomena can occur in other vehicles, said longtime aviation enthusiast Hugh Oldham of Anderson. "On a cold morning an automobile will emit white smoke, and water will drain from the exhaust pipe. It's the same concept as contrails."

Oldham, a University of South Carolina business graduate, is among those who are perplexed at the popularity of the theory that the contrails, which are visible world-wide, involve an intentionally sinister practice designed to harm those on ground level.

"That old saw (rumor) has been running around the internet for years," said Oldham, who questions the financial logic of the 'chemtrail' theory. "Why would any organization pay the expense to use high altitude aircraft to dispense some unknown chemical? If you want to dump chemicals, there are effective methods that are a lot more cost effective."

Another flaw in the theory that contrails are secretly chemically-laced: the secret could be easier kept by dumping the chemicals at night.

Reporters Georgie Silvarole, Abe Hardesty and Mike Ellis make up the A Team. Their weekly column is dedicated to answering any and all of our readers' questions. To submit a question, email ateam@independentmail.com or send a letter to the Independent Mail at 1000 Williamston Road, Anderson, SC 29621. The question-and-answer articles will appear in print on Saturdays.